Preferably, conventional office chairs are designed to provide significant levels of comfort and adjustability. Such chairs typically include a base which supports a tilt control mechanism to which a seat assembly and back assembly are movably interconnected. The tilt control mechanism includes a back upright which extends rearwardly and upwardly and supports the back assembly rearwardly adjacent to the seat assembly. The tilt control mechanism serves to interconnect the seat and back assembly so that they may tilt rearwardly together in response to movements by the chair occupant, and possibly to permit limited forward tilting of the seat and back. Further, such chairs typically permit the back to also move relative to the seat during such rearward tilting.
The chair also is designed to provide additional support assemblies to provide further support to the occupant's body at various locations thereof. In this regard, support assemblies have been provided which attempt to provide adjustable support to the lower back of the user in the lumber region thereof. However, one difficulty associated with the design of conventional office chairs is the fact that office workers have different physical characteristics and comfort preferences such that it is difficult to design a single chair configuration that satisfies the preferences of the different individuals who might purchase such a chair.
To improve comfort, it is known to provide lumbar supports which allow for adjustment of the elevation of the lumbar support along the back of the user. However, often times, such lumbar supports may be found uncomfortable to various individuals since they tend to provide localized pressure on the lumbar region of the back.
Accordingly, it is an object of the invention to overcome disadvantages associated with prior lumbar support arrangements.
The invention relates to a chair having an improved back assembly which provides support to the lumbar region of the chair occupant as well as to the pelvic region thereof. The back assembly of the invention includes a lumbar support arrangement disposed in the lumbar region of the back which is adjustable vertically to accommodate different sizes of chair users. Also, a pelvic support unit, i.e. pusher, may be provided vertically below the lumbar support to gently press upon the back of the user in the pelvic region thereof.
The back assembly is of the type having an open annular frame with a suspension fabric extending therebetween to close the central opening of the back frame. Since this suspension fabric is only a thin layer of material, the support provided by the lumbar support assembly is more readily felt and it is more critical to provide a comfortable lumbar support pad.
In an effort to provide optimum support to the back of the chair occupant, the lumbar support pad itself is formed of concentric support rings wherein radially adjacent pairs of such rings are flexibly joined together by connector webs extending therebetween. To a certain extent, each ring can independently move relative to an adjacent ring such that an outer ring would first contact an occupant and a next linear ring would then successively support the occupant as the occupant deflects the pad. This allows for greater variations in pressure being applied by each ring to the back of the user. Further, the lumbar support pad more readily adjusts to the shape of the occupant's back if the occupant presses sufficiently against the pad. The lumbar support thereby provides a desired amount of support while maintaining a proper ergonomic posture which does not depend upon movement of a lumbar pad toward or away from an occupant as in some prior art lumbar supports.
Additionally, the lumbar support pad is carried by a support arm formed similar to a leaf spring wherein the support arm has a vertically elongate opening in the middle thereof to separate the left and right halves of the support arm from each other along a substantial portion of the length of each support arm. While the support arm may bend rearwardly in response to the occupant, the bending point or fulcrum point for each of the left and right arm halves is independently adjustable so that the support provided to the lumbar support pad is asymmetric with respect to the left and right halves of the support pad. This support arm provides asymmetric support to the lumbar support pad and each half thereof may move more independently of the other in response to different loads or if remaining stationary, generate variable, asymmetric counter-pressure to the occupant which resists movement of the pad. The lumbar support arm provides varying rates of support for a given amount of deflection by repositioning the fulcrum point. The asymmetric support of the lumbar is adjustable by a pair of adjustment cranks which rotate independently of each other to adjust the fulcrum point of the respective arm halves without requiring or causing displacement of the pad. The chair occupant therefore can more accurately adjust the support provided by the support pad asymmetrically wherein it has been found that this asymmetric support provides improved comfort to the chair occupant.
Additionally, the pelvic support is provided vertically adjacent to the lumbar support to provide support to the different regions of the occupant's back. As described in further detail herein, the foregoing arrangement of a back assembly provides a more comfortable system for supporting the occupant's back.
Other objects and purposes of the invention, and variations thereof, will be apparent upon reading the following specification and inspecting the accompanying drawings.
Certain terminology will be used in the following description for convenience and reference only, and will not be limiting. For example, the words “upwardly”, “downwardly”, “rightwardly” and “leftwardly” will refer to directions in the drawings to which reference is made. The words “inwardly” and “outwardly” will refer to directions toward and away from, respectively, the geometric center of the arrangement and designated parts thereof. Said terminology will include the words specifically mentioned, derivatives thereof, and words of similar import.